Panopto 36: Male Germ Cells

Question 1

events relating to germ cell meiosis

Answer 1

1. replicate their DNA (before meiosis begins)
   result: chromosome # is the same still diploid and 46 chromosomes; what has changed is the amount of DNA on each chromosome, each chromosome now has 4 chromatids, whereas before it had 2 chromatids (DNA is doubled)

Question 2

chiasmata

Answer 2

happens after replication, where DNA strands link together. At this chiasmata crossing over occurs: exchange of DNA, which ensures genetic diversity because no 2 spermatozoa will be alike

Question 3

what is the first phase of meiosis

Answer 3

Meiosis I at the end of this, we get cell division (reduction division) This results in the formation of 2 cells; each cell will end up with a haploid number of chromosomes, but each chromosome still has double the amount of DNA (23 chromosomes instead of 46) In other words, we have haploid chromosomes and diploid DNA

Question 4

How long do secondary spermatocytes live?

Answer 4

8 hours in a human, and theyre hard to find on a microscope

Question 5

what do the cells from the first meoitic division turn into

Answer 5

secondary spermatocytes

Question 6

meiosis 2 end result

Answer 6

another cell division: equitorial division or separation of chromosomes, maintains the chromosome # (23 chromosomes), but DNA is then reduced. Now we have haploid # of DNA on haploid # of chromosomes

Question 7

what cell division produces spermatids?

Answer 7

equitorial division

Question 8

1 primary spermatocyte gives rise to how many spermatids?

Answer 8

4 spermatids

Question 9

transition from spermatid to spermatozoa

Answer 9

spermiogensis

Question 10

transition from spermatagonia to spermatazoa

Answer 10

spermatogensis

Question 11

which is a subset of which? Spermiogensis and spermatogensis

Answer 11

spermiogensis is a subset of spermatogensis

Question 12

what happens at spermiogensis

Answer 12

no more cell divisions
development of features that are characteristics of sperm cells (flagellum: tail, acrosome: sack of enzymes that let the male germ cell penetrate into the female germ cell, condensed chromatin, midpiece: has multiple mitochondria and forms the energy molecule the flagella uses (ATP), fructose to ATP to motility

Question 13

what comprises the sperm cell head?

Answer 13

acrosome and condensed chromatin

Question 14

spermiation

Answer 14

release from the wall into the lumen

Question 15

Spermatids initially had a lot of cytoplasm, and in the end there’s none. Why?

Answer 15

when they are released from the wall, the remnant is left behind and sertoli cells break it down and reuse the components

Question 16

residual body

Answer 16

cytoplasmic remnants that are left behind